Python- creating object instances in a loop with independent handling

Question

I have a simple election program. The following are the requirements:

class Politician
Randomized votes.

Taking number of politicians as input from user.

num_politicians = input("The number of politicians: ")

Looping and creating instances

names = []
for x in range(num_politicians):
    new_name = input("Name: ")
    while new_name in names:
        new_name = input("Please enter another name: ")
    names.append(new_name)

    #### This part is the crux of my problem
    ### Create instances of the Politician class
    #### I want to do this in a way so that i can independently 
    #### handle each instance when i randomize and assign votes

I have looked at:

However I could not find a solution to my problem

The Politician class is below:

class Politician:

    def __init__(self, name):
        self.name = str(name)
        self.age = age
        self.votes = 0

    def change(self):
        self.votes = self.votes + 1

    def __str__(self):
        return self.name + ": " + str(self.votes)

The Desired Output:

>>> The Number of politicians: 3
>>> Name: John
>>> Name: Joseph
>>> Name: Mary
>>> Processing...
(I use time.sleep(1.0) here)
>>> Mary: 8 votes
>>> John: 2 votes
>>> Joseph: 1 vote

My problem in one statement

I want to create class instances in the for-loop in such a way that i can assign them votes randomly (This would, I suppose, require me to independently handle instances.)

Any help would be appreciated.

I don't understand the question, by semantic, instance is independent. — marcadian
– marcadian, Commented May 24, 2015 at 6:14

martineau · Accepted Answer · 2015-05-24 09:19:52Z

You can store your instances in a list:

politicians = []
for name in 'ABC':
    politicians.append(Politician(name))

Now you can access individual instances:

>>> politicians[0].name
'A'

I used a modified version of your class that gives each politician a default age if no is provided:

class Politician:

    def __init__(self, name, age=45):
        self.name = str(name)
        self.age = age
        self.votes = 0

    def change(self):
        self.votes = self.votes + 1

    def __str__(self):
        return self.name + ": " + str(self.votes)

Now you can work with your list of politicians:

print('The Number of politicians: {}'.format(len(politicians)))

prints:

The Number of politicians: 3

this:

for politician in politicians:
    print(politician)

prints:

A: 0
B: 0
C: 0

Assign random votes:

import random

for x in range(100):
    pol = random.choice(politicians)
    pol.votes += 1

Now:

for politician in politicians:
    print(politician)

prints:

A: 35
B: 37
C: 28

The whole program:

# Assuming Python 3.

class Politician:

    def __init__(self, name, age=45):
        self.name = str(name)
        self.age = age
        self.votes = 0

    def change(self):
        self.votes = self.votes + 1

    def __str__(self):
        return '{}: {} votes'.format(self.name, self.votes)

num_politicians = int(input("The number of politicians: "))
politicians = []
for n in range(num_politicians):
    if n == 0:
        new_name = input("Please enter a name: ")
    else:
        new_name = input("Please enter another name: ")
    politicians.append(Politician(new_name))

print('The Number of politicians: {}'.format(len(politicians)))
for politician in politicians:
    print(politician)

print('Processing ...')
for x in range(100):
    pol = random.choice(politicians)
    pol.votes += 1

for politician in politicians:
    print(politician)

And the usage:

The number of politicians: 3
Please enter a name: John
Please enter another name: Joseph
Please enter another name: Mary
The Number of politicians: 3
John: 0 votes
Joseph: 0 votes
Mary: 0 votes
Processing ...
John: 25 votes
Joseph: 39 votes
Mary: 36 votes

UPDATE

As @martineau suggests, for real-live problems a dictionary would be more useful.

Create dictionary instead of a list:

politicians = {}

and in the loop us the name as key when you add your instance:

politicians[new_name] = Politician(new_name)

I would suggest storing the Politician instances in a dictionary keyed on their name since in real life that how votes are cast (as opposed to randomly selecting one from a list of them).
@martineau Agree. Added some lines to my answer suggesting this improvement.

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